Chris Christie: “If we want to be a winning party again, we got to look forwards and go after Joe Biden.”

This is against type for him. I'm sure it was a difficult decision. I think his analysis was, he cannot live with a nuclear weapon in Iran, and Israel did all of the heavy lifting.

It makes this debate really crucial. It's an amazing timing by him, because it is a race for second in Iowa.

What Reagan would do is if there was parts of it he didn't like, he'd get in there and negotiate it and try to make it better.

What poses a national security risk is the possibility that he could be president of the United States again.